LOCKPORT -- The FBI has opened a child pornography investigation against a North Tonawanda man already charged with sexually assaulting a 12-year-old girl at knifepoint.

The Buffalo News learned from a federal law enforcement source this week that child pornography charges against Mitchell W. Brokob, 41, are being considered, based on an inspection of computers seized by North Tonawanda police from his Gilmore Avenue home June 6.

That was the day Brokob was charged with abducting the 12-year-old girl March 20 as she walked past his home on the way to school and assaulting her in a vacant house three doors away.

Niagara County Assistant District Attorney Elizabeth R. Donatello opened a hearing in Niagara County Court on Wednesday by telling Judge Matthew J. Murphy III that the hearing would not be exploring the legality of the computer seizure, as had been announced when the session was scheduled last week.

"We are leaving that for federal prosecution," Donatello told the judge.

At last week's court appearance, Brokob rejected an offer to plead guilty to the North Tonawanda sexual assault and two other child molestation cases dating back six years in Lackawanna. Erie County prosecutors are preparing charges in at least one of those cases, District Attorney Frank J. Clark said last week.

The deal Brokob rejected would have limited his prison time to 25 years. He faces a possible sentence of life in prison if convicted of predatory sexual assault in a trial scheduled to begin here Nov. 10.

One of his attorneys, Assistant Public Defender Michael E. Benedict, has said Brokob didn't want to plead guilty to the Lackawanna charges. Brokob grew up in that city and lived there until moving to North Tonawanda a few years ago.

In an interview after Wednesday's hearing, Donatello said the child pornography probe "has nothing to do with any plea negotiations at all."

She said the Niagara County district attorney's office decided on its own to turn the computers over to the feds.

"We made the decision that the investigation of the computers and their contents would be best in the hands of the FBI and the U.S. attorney's office, as their sentencing guidelines carry a significantly higher sentence [than state law does]," Donatello said.

While the maximum sentence under state law for possessing child pornography is four years in prison, federal law carries a mandatory minimum sentence of five years, a figure that rises rapidly depending on the number of images and the defendant's criminal history.

In testimony Wednesday, North Tonawanda Police Detective Karen Smith said she and Niagara County Sheriff's Investigator Kristen Neubauer visited Brokob's home April 19, the day police went door-to-door seeking DNA samples from men in the neighborhood who matched the girl's general description of her masked attacker. Smith said Brokob made no fuss, signed a consent form and rubbed the inside of his cheeks with two swabs to give the samples.

Smith also said she noticed a video camera mounted on the porch. Brokob told her it was installed after the March 20 incident and was supposed to track traffic. However, Detective Larry W. Kuebler testified that when he seized the camera June 10, it was pointed at a playground across the street.

Smith said that Brokob said he hadn't seen the girl pass his house on the morning of March 20, asserting that he slept until almost 9 a.m., or about two hours after the girl said she was grabbed. He said he didn't see the girl run past his house about 10 a.m., either. That's when the girl said she left the vacant house.

Kuebler testified that Brokob's wife, Cynthia, gave him and Smith permission to search the couple's home June 10.

In the master bedroom, they found two newspaper clippings about the case in Brokob's nightstand, and in a closet, a shoe box containing what Smith called "a sexual card game and four sexual performance aids." On cross-examination, she called them "sex toys."

Kuebler said they were looking for such items, along with videos, compact discs and cassettes, after he interviewed Cynthia Brokob earlier that day. She mentioned recording devices inside the home and gave him a camcorder and cables, Kuebler said.